System for performing hip prosethesis revision surgery

ABSTRACT

A system for performing hip prosthesis revision surgery includes a trial femoral component having a passageway which, upon insertion in the cavity left after removal of the original prosthesis, provides guide means for drilling a channel to receive a guide wire which, upon removal of the trial femoral component, serves as guide means for progressively larger reamers.

This is a divisional of copending application Ser. No. 07/565,149 filedon Aug. 10, 1990, now U.S. Pat. No. 5,047,035.

BACKGROUND OF THE INVENTION

The present invention is directed to a system for performing revisionsurgery to replace a hip prosthesis having a stem portion previouslyimplanted in a cement mantle in the intramedullary canal of a femur andto a system for performing such surgery.

As is well known, it is frequently necessary to replace a hip jointprosthesis. This is usually done several years after the originalimplantation in order to replace disfunctional joints or to obtain thebenefits of one of newer design which resulted from advancements inmedical technology.

In the course of hip revision surgery, it is necessary to remove thefemoral component including its stem form the intramedullary canal ofthe femur. The cement material utilized to fix the stem within theintramedullary canal must be removed prior to implantation of the newprosthesis therein. Removal of the cement is accomplished by drilling orreaming. During such drilling or reaming procedure, it is important thatthe drill or reamer or properly aligned and guided to avoid accidentalperforation of the cortex of the femur.

A number of prior art devices have been utilized for aligning drills orreamers in the performance of revision hip surgery. U.S. Pat. No.4,860,735 relates to a drill alignment guide for osteoplastic surgery inwhich an alignment rod is supported on a clamp element affixed to thefemur. The drill is mounted for movement with an alignment rod which isparallel to and disposed a predetermined distance from a shaft of thedrill. As the drill is moved forward, the forward end of the alignmentrod moves through an aperture of the clamp element thereby insuring thatdrilling occurs along a predetermined drilled path extending along thebone axis.

U.S. Pat. No. 4,686,972 relates to a surgical deflector and drillingguide for guiding a drill bit, awl or reamer into a bone. Theboring-tool guide assembly comprises a sleeve having a T-shaped nibwhich can be detachably inserted into a corresponding bracketpermanently mounted against a tool having teeth designed to anchor thetool in a boney tissue. The surgeon can insert the tip of a drill bit,awl or reamer into the sleeve of the guide assembly when the teeth areanchored onto a boney tissue to obtain means for guiding the boringtool.

A method of economically removing cement from the femoral canal duringrevision surgery appeared in the publication "Orthopedics Today",September 1989, pages 18 and 19. Under the procedure described therein,a side cut and end cut reamer positioned in a guide sleeve is utilizedto remove the cement.

A catalog entitled "Omiflex™ Femoral System Surgical Protocol Press-Fit"copyright 1988 by Osteonics Corp., describes a cement removal systemutilizing a tapered axial reamer.

U.S. Pat. No. 4,919,673 is directed to a femoral head prosthesis havinga fixing stem with a longitudinal bore utilizing a centering rodextending therethrough and engaged to a barrier at the lower end of thebone cavity.

The foregoing prior art references are incorporated herein by referenceand copes are herewith enclosed.

SUMMARY OF THE INVENTION

The present invention provides for a new system of performing revisionsurgery utilizing improved means for insuring proper centering andguidance for of the reamer utilized for removing old bone cement. Suchcentering and guidance means insures proper positioning of the revisionprosthesis with an adequate thickness of bone cement there around andassists in avoiding accidental perforation of the cortex of the femur.Under the present invention, the original femoral component is removedand then replaced by a cannulated trial femoral component of similarsize and shape to the original prosthesis which has been removed. X-raystaken prior to removal of the original prosthesis can be used to confirmthat the original prosthesis is still properly aligned in the femuralcanal and did not subside within the original cement mantle into varus.Assuming that the original prosthesis as removed was properly aligned,the cannulated trial femoral component is then inserted into the cavityleft by the removal of the original prosthesis. An elongated drill isthen inserted through the cannulated stem and, using the passageway ofthe cannulated stem as a guide, is utilized to drill through the cementand cement restricter at the bottom of the cavity thus forming a pilothole in the cement, restricter and bone marrow therebelow. The pilothole is sufficiently large to permit insertion of a bullit guide wirehaving a slightly enlarged head at its free end. Following insertion ofthe bullit guide wire, cannulated reamers of progressively increasingsize are placed over the bullit guide wire and utilized to progressivelyincrease the size of the prepared canal to (1) remove all of the oldbone cement, centralizer and restrictor and (2) reach a size suitablefor receiving new bone cement and the stem of the new femoral hip jointprosthesis.

The invention will be more fully understood and other objects andadvantages will becomes apparent form the following detailed descriptionin conjunction with the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an elevational view, partially in section, showing the femoralhip joint prosthesis implanted in the femoral canal of a patient.

FIG. 2 is a view similar to FIG. 1 showing the femur with the previouslyimplanted femoral hip joint prosthesis removed.

FIG. 3 is a view similar to FIGS. 1 and 2 showing the cannulated trialfemoral component of the present invention positioned within the cavitypreviously occupied by the original femoral hip joint prosthesis.

FIG. 4 is a view similar to FIG. 3 but showing the drilling of a pilotpassageway utilizing the cannulated trial femoral component as a guide.

FIG. 5 is a view similar to FIG. 4 following removal of the elongateddrill bit and insertion of the guide wire with its enlarged bullit headthrough the guide passageway of the cannulated trial femoral componentand into the newly drilled pilot hole.

FIG. 6 is a view similar to FIG. 5 but slightly enlarged for clarity,showing the reaming of the canal following removal of the cannulatedtrial stem and showing the first of several progressively larger reamersbeing utilized with the bullit guide wire as a guide to control the pathof the reamer.

FIGS. 7 and 8 are view similar to FIG. 6 showing the femur as the canalis progressively enlarged with still larger reamers utilizing the bullitguide wire as a guide.

FIG. 9 is a sectional view of a femur prepared for revision surgery withthe old cement removed and the guide wire removed.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to FIG. 1, there is shown a femur generally designated bythe number 10 having implanted therein a hip joint prosthesis 11 havinga stem 12 implanted within the intramedullary canal 13 of the femur. Thestem extends from a lower distal end 14 to an upper portion whichincludes an enlarged shoulder 15 and a neck portion 16 disposed at anobtuse angle relative to the stem 12.

The prosthesis 11 is typically secured in the femoral intramedullarycanal 13 by a cement mantle 17 of polymethylmethacrylate (PMMA) or othersuitable bone cement. A restrictor 18 is placed in the intramedullarycanal 13 prior to introduction of the bone cement 17 therein. The distalend 14 of the stem may be engaged in a centralizer 19 which assists incentering the distal end 14 during the step of implantation of theprosthesis 11 in the cement 17. The prosthesis 11 may be provided withan aperture 20 or other suitable grasping means to assist in itsremoval. As shown in FIG. 2, the removal of the prosthesis 11 leaves acavity 25 conforming to the shape of the removed stem 12. Obviously,prior to removal of the prosthesis 11, any portion of the cement mantle17 such as that overlying the enlarged shoulder 15 as indicated by thenumeral 26 in FIG. 1, must be removed. As can be seen in FIG. 2, therestrictor 18 and centralizer 19 remain within the intramedullary canal13 following removal of the prosthesis 11 as does the cement mantle 17which retained the prosthesis 11.

It is desirable that all of the old cement 17 be removed prior toimplantation of a new prosthesis in the intramedullary canal 13. Inorder to effect such cement removal efficiently and with minimal risk tothe patient, the present invention provides guide means for the drilland reamer utilized for such removal. Referring to FIG. 3, there isshown a cannulated trail femoral component 30 of the present inventionfollowing its insertion into the cavity 25 left by removal of theoriginal prosthesis 11. The cannulated trial femoral component 30preferably has a stem 31 which is shaped substantially the same as theshape of the stem of the original prosthesis 11. The stem 31 extendsfrom a distal end 32 to an enlarged upper end 34 extending out of thecavity 25. The stem 31 has a longitudinally extending passageway 33which extends from the distal end 32 to the upper end 34 where it formsan outlet opening 35.

Prior to removal of the original prosthesis 11, X-rays should be takento determine that the stem 12 of such original prosthesis was properlyaligned to the intramedullary canal 13 and that is did not shift intovarus as a result of subsidence within the cement mantle. Suchsubsidence within the cement mantle is known to occur over a period oftime.

As shown in FIG. 4, there is provided a drill 40 having an elongateddrill bit 41. The drill bit 41 has a length permitting it to extendcompletely through the longitudinal passageway 33 of the cannulatedtrail femoral component 30 and a substantial distance beyond. Thus, asshown in FIG. 4, the drill bit 41 is of sufficient length to drill,using the longitudinal passageway 33 as a guide, through the centralizer19, restricter 18 and a substantial distance into the intramedullarycanal 13 forming a new channel 42 below the restricter 18.

Referring not to FIG. 5, there is shown a built guide wire 43 having anenlarged head 44 positioned in the newly drilled channel 42.

Thus, following drilling of the channel 42 through the centralizer 19,restricter 18 and further into the intramedullary canal 13, the drillbit 41 is removed therefrom while leaving the cannulated trial femoralcomponent 30 positioned therein. Thereafter, the guide wire 43 with itsenlarged head 44 is inserted through the longitudinal passageway 33 andinto the channel 42. Following insertion of the guide wire 43, thecannulated trial femoral component 30 is removed leaving the guide wire43 in position.

Referring now to FIG. 6, following removal of the cannulated trialfemoral component 30, a reamer 50 having a hollow stem 51 terminating inan enlarged cutting head 52 is provided. A longitudinal passageway 53extends through the cutting head 52 and the stem 51. The reamer 50 istelescoped over the bullit guide wire 43 and may be power rotated by anystandard well known power means.

As can be seen in FIGS. 7 and 8, progressively larger reamers 50' (FIG.7) and 50" (FIG. 8) with progressively larger cutting heads 52' and 52"are utilized to progressively enlarge the opening of the cavity 25 andremove the old cement 17, the centralizer 19 and the restricter 18 andto progressively enlarge the opening until all of the old cement 17 hasbeen removed and in doing so to utilized the bullit guide wire 43 toguide it. If desired, as progressively larger reamers 50, 50' and 50"are used, larger diameter guide wires may be inserted, replacing thesmall guide wire 43 used for the drill bit 41. The larger guide wireswill give additional rigidity in guiding the path of the reamers.

Referring to FIG. 9, following reaming of the old cement 17 in the lowerportion of the femur and reaming of the centralizer 19 and restricter18, the reamer and guide wires 43 may be removed. Although there will beadditional old cement 17 still present in the upper, larger femurportion, it can be readily removed by conventional techniques.

It is to be understood that the above detailed description of apreferred embodiment of the invention is provided by way of exampleonly. Various details of design and construction and steps in theprocedure may be modified without departing from the true spirit andscope of the invention as set forth in the appended claims.

We claim:
 1. For use in performing revision surgery to replace a hipprosthesis having a stem portion previously implanted in a cement mantlein the medullary canal of a femur, the combination comprising:(a) atrail prosthesis having a stem extending from a distal end to a proximalend, said stem having a passageway extending longitudinally throughoutits length from said distal end to said proximal end; (b) drill meanssized to be received within said passageway for forming a pilotpassageway in said medullary canal using the passageway of said trialprosthesis as a guide; and (c) cannulated reamer means sized to fit oversaid drill means for enlarging said pilot passageway following removalof said trial prosthesis using said drill means as a guide.
 2. For usein performing revision surgery to replace a hip prosthesis having a stemportion previously implanted mantle in the medullary canal of a femur,the combination comprising:(a) a trial prosthesis having a stemextending from a distal end to a proximal end, said stem having apassageway extending longitudinally throughout its length from saiddistal end to said enlarged shoulder; (b) drill means sized to bereceived within said passageway for forming a pilot passageway in saidmedullary canal using the passageway of said trial prosthesis as aguide; (c) guide wire means sized for positioning in said pilotpassageway; and (d) cannulated reamer means sized to fit over said drillmeans for enlarging said pilot passageway using said guide wire means asa guide.
 3. The combination according to claim 2 further including aplurality of progressively larger cannulated reamer means.
 4. Thecombination according to claim 2, wherein said guide wire means has anenlarged head.
 5. The combination according to claim 2 further includingat least one additional guide wire having greater size and rigidity thansaid guide wire means.